1. Field of the Invention
The present invention relates to a housing for a Cigarette Lighter Adapter (CLA) or accessory adapter plug housing which facilitates insertion of a CLA or accessory adapter plug into a receptacle.
2. Description of the Prior Art
Various portable devices and appliances, such as cellular phones, are known to use rechargeable batteries. For example, lithium ion batteries are known to be used in such applications. Battery chargers for such lithium ion batteries are generally known in the art. Examples of such lithium ion battery chargers are disclosed in U.S. Pat. Nos. 5,670,862; 6,586,130 and commonly owned U.S. Pat. Nos. 5,764,030 and 6,002,237. Various types of battery chargers are known. In particular both desk top and portable battery chargers are known.
U.S. published patent application US 2002/0117996A1 illustrates a desk-top type housing. Such desk top battery chargers are known to include an AC-DC converter and are configured to be plugged into a conventional 120 volt AC receptacle.
Portable battery chargers are also known and include a cigarette lighter adapter (CLA) or accessory adapter plug configured to be received in a vehicle CLA or accessory adapter receptacle. Such portable battery chargers include a DC-DC converter for converting the vehicle DC voltage to a voltage suitable for the battery to be charged.
Due to the configuration of a vehicle CLA receptacle, some CLA plugs are known to be cylindrical in shape. Such CLA plugs are also known to include a pair of oppositely disposed radial spring contacts that extent outwardly from the plug housing. These radial spring contacts are adapted to make contact with a negative contact within a CLA or accessory adapter receptacle. Depending on the spring constant of the radial spring contacts, the amount of axial force required to insert a CLA or accessory adapter plug into a receptacle will vary. It is also known that the tighter the contact between the radial spring contacts and the negative contact within the CLA or accessory adapter receptacle, the better the electrical contact. In order to provide a tight contact between the radial spring contacts and the negative contact within the plug, the spring constant of the radial spring contacts needs to be relatively high. Unfortunately, with such a configuration, the axial force required to insert the CLA or accessory adapter plug into the receptacle is relatively large causing it to be relatively difficult for an end user to insert the plug into the receptacle. The problem is exacerbated when the CLA or accessory adapter plug is formed with a relatively constant diameter cylindrical housing which does not provide a suitable gripping surface for the user. Thus, there is a need for a CLA and accessory adapter plug configuration which facilitates insertion of a CLA or accessory adapter plug into a receptacle.